Nitrided steel and a process for its production



Patented Feb- 4, 1 936" V UNITED" STATE PATENT OFFICE NITBIDED STEELANDA PROCESS FOR ITS PRODUCTION I Wilhelm rn-eu. Luxemburg, Luxemburg NoDrawing. Application January 6, 1931, Serial No. 506,973. In GermanyJanuary 18, 1930 11 Claims. (omit-1c) The invention relates to nitridedsteel and a Itis well-known that invar-steels contain about process forits production. 36% of nickel It is already known that iron as well ascertain iclaim: alloyed steels can be superficially nitrided by 1. As anew article of manufacture, a steel havheating in a current of ammoniaat temperatures ing a nitrided surface layer and containing from 5between 500 and 800 C. (nitriding) In par- .1 to 5% of beryllium, theprincipal portion of the ticular chrome-aluminium steels are nitrided atremainder being irOua temperature below 580 at which there is still 2.As a new article of manufacture, a steel havproduced no coating tendingto form splinters. ing a nitrided surface layer and containing from Theinvention relates to the use of beryllium- .1 to 5% of beryllium, andabout from to 12% 0 containing steels such as nitrided steels and to aof nickel, the principal portion of the remainder process for thenitriding of these steels. By being iron. means of experiments it hasbeen found that 3. Asanew article of manufacture, asteelhavberyllium-nitrided steels possess great technical ing a nitridedsurface layer and containing from advantages. g

i As is well known beryllium'steels, in particular nickel and about from10 to of chromium, those alloyed with nickel, also chrome-containtheprincipal portion ofthe remainder being iron. in beryllium steels willage ifafter chilling from. As a ewj u a ture; a steel ahighe'r range oftemperature they are subjected chil ed fr m a t m ratu e above that ofaging 20 to the so -called artifloial'ageing, that is to say andsubsequently heated in an atmosphere con- 20 to a subsequent heattreatment at temperatures tainine' nitrogen to mp tur f fr m 4 betweenabout 400 to 600913. The chilled beryl-1 C- until ni o n ha pnetratedlnto its lium steels by such ageing process attain theirsurfacet'o form a nitrided layer, d S l 00ngreat hardness at thosetemperatures at which taining from t f eryl m, 'prig cip nitriding isconducted. Consequently according portion of the remainder being iron.to the invention it is possible by nitrid'ing to coat 5. As a newarticle of m ufa r a st e a beryllium steel which in the aged state hasa ch d m a mp r u ebOVe that 0! in hardness of BOO-700 Brinell, with acoating as and subsequently heated in an atmosphere conhard as glass,which is impossible with the orditaining nitrogen to a temperatureoffrom 400 to nary chilled steels because the steel is already 600 C.until nitrogen has penetrated into its annealed by the nitridingtemperatures. By the 1 form 8; n y r, Said St el 6011- use of myinvention I can produce a metal body tami g from .1 to 5% f b ryllium adb0u or article which possesses a core as hard as steel from 10 to 1.2%of nickel, the principal portion and a surface as hard as glass. As,furthermore, -0f the remainder bein l beryllium has a rather'considerable amnity for 6. As a' new article of manufacture, a steelnitrogen the carrying out ofthe nitriding process c lled ronts temperaure above that of aging is facilitated and generally"speaking the workand subsequently heated in an atmosphere concan be done with nitridingtemperatures of taining trogento a temp of from 400 to 500 0. 600 C.until nitrogen has penetrated into' its .1 to 5% of beryllium, aboutfrom 10 to 12% of 15.

t It ispossible bya single operation, to age berylsurface to form anitrided layer, said steel con-; 40 I lium steels artificially and.atthe same time to taining from .1 to 5% of ry m f nitride them Ifdesired, howev'erfthe nitriding t0 of nic a a ut f 'Om 10 O- .01 can beeffected after the artificial ageing of the chromium, th'e'principalportion of the remainder beryllium steels. bein iron.

It has been found that the best results are ob- "7 The process ofimproving the, hardness of tained when the percentage of beryllium is besteel containing from .1 to 5% .of beryllium, the tween 0,1 and5%. Insome cases somewhat more principal portion of the remainder being iron,or somewhat less beryllium can beused, Espewhich process consists inchilling the steel from cially favourable properties areexhibited by aatemperature above that of. aging and subsenitrided steel with 10-12%nickel, say with about quently nitriding it superficially while heatingit justas much chromium arid 1% beryllium. The to a temperature of from400 to 600 C. percentage of chromium may if desired be in- 8. Theprocess of improving the hardnessof f creased to over 20%. Invar-steelsare also capa steel containing from .1 to 5% of beryllium and ble ofbeing nitrided provided they contain about from .10 to 12% oif niclrel,the principal beryllium. portion of the remainder being iron, whichpr0'0- 5 ess consists in chilling the steel from a temperature abovethat of aging and subsequently nitriding it superficially while heatingit to a temperature of from 400 to 600 C. I

9. The process of improvingthe hardness of steel containing from .1 to5% of beryllium, about IromplO to 12% of-nickel andabout from 10 to 20%of chromium, the principalportion of the remainder being iron, whichprocessconsists in chilling the steel from a temperature above that ofaging and subsequently nitriding it superficially while heating it to a.temperature of from 400 to 600 C. to produce a nitrided surface.

. 10.:As anew article of 'manufacture, a steel having a nitrided surfacelayer and containing from .1- to 5% 01' beryllium,

and about 36% of nickel, e principal portion oi the remainder being n-1'1.'As a newarticle of manufacture, a steel chilled from 'a temperatureabove that of aging subsequently heated in an atmosphere containingnitrogen to a temperature or from 400 tocoo" 0. m nitrogen haspenetrated into its steel surface to form a nitrided layer, saidsteel-containing from .1 to 5% ol beryllium and about 36% of nickel, theprincipal portion 01' "the remainder being iron.

12. The process-of improving the hardness of containing from .1 to 5% orberyllium and about 36% of nickel, "the principal portion of theremainder being iron, which process consists in chilling thesteel from atemperature above that of aging and subsequently nitriding itsuperficially while-heating it to a temperature of from 400 to 600 C. 1

13. As a new article of manufacture, a nickelalloy steel having anitrided surface layer and containing from .1 to 5% of beryllium, theprincipal portion of the remainder being iron.

14. As a new article of manufacture, a nickelchromium-a oy steel havinga'nltrided surface layer and co 'tainin'g from..1 to'5% of beryllium,the principal iron..

" mm rmbm} portion of the remainder being a

